1. Field of the Invention:
The present invention concerns improvement in systems for the adjustment of the angular position of parts in rotational movement by means of an object connected to the moving part and having discontinuities in shape or material, and by means of a single sensor for supplying regular signals whenever the shaft is in given angular positions and for forming a reference signal.
2. Description of the Prior Art
In an automobile, for example, an impulse transmitter is used which supplies a signal whenever the crankshaft is in a given position (for example, at the high dead point or bottom of the engine cycle relative to one or more cylinders) and which supplies a series of impulses for determining the exact angular position of the crankshaft. In order to generate these two types of signals, a disk having a tooth at the points of reference is generally placed next to a toothed disk having a number of raised teeth. This operation is burdensome and difficult to perform because of the space required by the device, the number of targets and sensors and the difficulty of obtaining synchronized signals following thorough adjustment of the two targets.
Others have attempted to avoid these disadvantages using a single sensor by eliminating a tooth of the target or by adding a tooth locally and detecting the discontinuity thus produced so as to produce an adjustment impulse upon the passing of the first tooth following the discontinuity.
Nevertheless, these systems involve several disadvantages: on the one hand, they require an impulse rate having a cyclic ratio of one between the width of the tooth and the space between the teeth, which is difficult to obtain in practice where the target is often slightly out of round or, in the case of cold-starting an internal combustion engine, when very large variations of instantaneous speed are observed, on the order of 1 to 10 over a half turn, throwing off all presently used systems. Furthermore, placing the discontinuities on the dead points, as is often described, involves disadvantages in the starting phases since the differential quotient of the angular speed is cancelled out and changes sign at the moment the discontinuity passes. There then remains the possibility of placing the discontinuity at a point more favorable for its detection, but in this case the information on passage of the dead points is no longer given.